Refrigerating apparatus



P 1952 J. E. WOODS 2,608,832

REFRIGERATING APPARATUS Filed Oct. 8, 1949 Patented Sept. 2, 1952 UNITED STATES PATENT 2,608,832 l I ZREFRIGERATING A PA TUS v H John' E. 'Woods, Cohasset, Mass., ,assignor Standard-Thomson Corporation, Boston, Mass., acorpora tion of Delaware v I; Applica.ti0i1 October 8, 1949, Serial N0;"120,3 15 a l 3 4 Claims. (01.62-91.53 I

T The present invention'relates to refrigerating systems, and more particularly to temperature control systems useful in connection with refrigeratingapparatus described in the Brunsing Patent 2,450,713, and my copending application filed of even date herewith.

@The apparatus there described uses Dry Ice to cool azliquid refrigerant, which is in turn used to .cool the refrigerated space. The refrigerant is circulated by thepressu're from a separate tank of Dry Ice, and its flow is regulated by thermostatically controlled valves.

Consideration has been given to the use of a system of this general type for cooling freight cars carrying perishable foods, such as lettuce, celery and spinach. These vegetables must be kept at a temperature of about 40 F. In the Brunsing system the cooling coils are usually at a temperature of approximately 0 F. to F. This causes the'moisture of the air to condense and freeze on the cooling'co ils, therebylowering the humidity of the car and causing the vegetables to become dehydrated.

The object of fthe present invention is to provide a temperature control system; which will keep-the temperature in therefrigerated space at a pore-determined level without allowing the temperature of thecoolingcoils to fall below the freezing point. i I With thisobject inview, the principalfeature of the present invention contemplates the division of the refrigerant returning from the cooling coils into two streams, only one of which is circulated through the cooling coils. These two streams are then mixed by a thermostatically controlled valve which maintains the refrigerant at some pre-determined intermediate temperature. .If the body of the freight car is to be kept at 40 F., the mixing valve may be set to maintain the refrigerant at a temperature of 33, F. Refrigerant of this temperature is sufiiciently cold to refrigerate the car, but not cold enough to cause the condensate on the cooling coils to freeze. Thus dehumidiflcation of the cargo is avoided.

The accompanying drawing is a diagram of the preferred apparatus according to the present invention.

In the drawing the freight car 2 is indicated in outline. The car has at one end a cooling space ordinarily of the type used as an ice bunker, bounded by the wall 4, which-completely separates the bunker from the body of the car.

On the floor of this space is a series of cooling pipes or coils 6 connected with headers 8 and adapted to support a considerable quantitybf Dry Ice. Contained within the tubes andheaders is a' circulating cooling medium which may be an alcohol, an ethylene glycol mixture or any suitable material having a sufliciently low freezingpoint'so that it remains. fluid at thetemperature 'encounteredintheDry Ice system.- This'material is sometimes referr.ed-;to as brine".

even though it contains nosalt. The storage space in which the Dry. Ice is containedimay be referred to asthe- Dry Ice bunker. This bunker may contain several thousand pounds of Dry Ice which is in intimate heat exchange relation with the cooling coils;

Immediately beside the Dry. Ice bunker is acontainer .IZ which is referred to as the vDry Icepressure tank. This container holds a relatively small quantity of Dry Ice which isiused asa' means of generating pressure for the circulating medium.

Two chambers, I4 and l 8,v circulating. medium.v vAbove thefichamberll is .a

float chamber Hi, which-re'ceives:..the warm refrigeran't. The compartment 19 above the float chamber. contains valves and piping-which, are described in my above-mentioned copending application.

A pipe 20 connects" the bottomfofxthelchamber I8"with"one of the headers .8 of: the, cooling coils;

through a-mixingva'lve '23? (to belaterdescribed) with ceiling coils 24 preferably. located; near the; top of theycar. coils 24 through thermostatic control valves '21 to a line "leading 'to thefloatchamberJ-Br;

Pipes Hand 30 lead from the Dry Ice pressure tank into the chambers l4 and. 18-1 toiapply,

pressure continuously thereto. A- pipe :3l leads from'the pressure tank l2 to .thevalve, chamber H which contains a valve controlled .by a float in the chamber 16. A -pipe 32 leads from the float chamber into the tank l8 and a pipe 33 leads from the float chamber into the tank l4, both of these pipes being provided with check valves to prevent back flow of fluid when the float chamber is vented to atmosphere.

Except for the chamber l4, the connections thereto, and the mixing valve, the parts thus far described are similar to those of my copending application, and are not here described in detail. It is sufiicient to note that the valve mechanism in the chamber l9 applies pressure intermittently to the float chamber Hi. This mechanism is operated by a float in the chamber I6.- When the refrigerant coming from the coolare provided for the" Return pipes 26 lead fromthe.

ing coils 24 rises to a certain level in the float chamber, the float trips a valve which then apthe float again operates the valve mechanism,

and vents the float chamber to atmosphere. This chamber and tanks, pipe connections from the restores the pressure differential in the-system which causes the refrigerant to circulate from I 8 through the cooling coils and back to l8 as above described. It will be under'stood that the circulation of refrigerant is under the control of the thermostatic valves 21, whereby circula tion is shut ofi except when the temperature in the car has risen to such a point that refrigeration is called for.

A line 36 connectsthe tank l4 directly with the mixing valve 23] Since the refrigerant. circulated from tank I4 is notico'oled; tank lil may be termed the warm .brine: tank; .Here the cold stream through ZZ'and the warm stream through 36 'aremixed. The mixing valve: is of 'conyen-i' the warm-brine stream is cut off and-only the cold refrigerant is circulated. :At the. same time. valve is turned tozby-p'assthe cold refrigerant aroundith'e mixing valve-.: The system then op:-

erates in the manner described inzmy vcopendingapplication. I r

Having thus described my invention, .Lclaim': l. A- refrigerating'systemicomprising a heat exchanger for'cooling'afluidrefrigerant,-m-eansv for maintaining a supply ofIDryIce to .cool the refrigez antga container for Dry Ice 'toprovide pressure for circulating therefrigerantfa chamber for receiving the circulatedivarm refrigerant, a pair of tanksfpipe connections between the tanks andchamber so disposed that part of the warm refrigerant'flows into each tank, means for passing the refrigerant from one ofthe tanks through said heat exchanger, and arnixing' valve for mixing the refrigerant thus cooled with warmrefrigerant from thelother tank toprovide a co'oling m'edium saving a sufflcientlyhigh temperature to re-' vent excessive dehumidification of the space to be cooled.

2. A refrigerating system comprising a heat exchanger for cooling a fluid refrigerant, means for maintaining a supply of Dry Ice to cool the refrigerant, a container for Dry Ice to provide pressure for circulating the refrigerant, a float chamber to receive circulated warm refrigerant, 'apair of tanks located belowthe level of the float chamber, pipe connections between the float pressurecontainer for applying pressure to the tanks, and a thermostatically controlled mixing valve-formixingthe refrigerant cooled by the *h'eatj exchanger with warm refrigerant to provide a coolingniedium'having a sufiiciently high temperature to prevent excessive dehumidification of the space to be cooled.

31A refrigerating system comprising a heat exchanger for cooling allfluid refrigerant, means formaintaining a supply of Dry;Iceto cool the refrigerant, a container for Dry Ice to provide pressure for circulating the refrigerant, a float chamber to receive circulated warm. refrigerant, collecting means for warmrefrigerant located below the level of the floatchamben'pipesconnections ibetween the-float chamber and collecting means, connections fromthe pressure container for applying pressure to the collecting :means, a connection from the .collecting means'to the heat exchanger and a thermostatically controlled-mixing valve for mixing the refrigerant cooled by the heat exchangerwith warm refrigerant from the collecting means to provide a cooling medium having a sufiiciently high-temperature to prevent excessive dehumidiflcation of the :space to be cooled.

- 4; A refrigerating system comprising aheat exchanger for cooling :a fluid'refrigerant, means for maintaining a supply of 'DryIce to cool the refrigerant, a container for Dry Ice to provide pressure for circulating the :refrigerant, a float chamber to receive circulatediwarmrefrigerant, collecting means for warm refrigerantlocated below the levelof the float chamber, means fordividing the circulated warm refrigerant into two streams means for: passing one of-the streams through the heat exchanger, and a mixing valve to mix the two streams to provide a cooling .me-' dium having a sufliciently high temperature to prevent excessive, .dehumidification-of the space JOHN E.- WOODS-.

7 v REFERENCES CITED Thes'following references are of record in the file of this patent: l

V UNITED STA E PATENTS Number, Name Date 2,301,938 Fator Nov. 17, 19 2 23501713 Brunsing Oct. 5, 1948 

